Method and apparatus for determining an electrical torque of an electrical machine

摘要

A method for determining an electrical torque of an electrical machine includes determining an electrical torque in a first speed range with a first algorithm, and determining the electrical torque in a second speed range with a second algorithm which differs from the first algorithm. An upper limit of the second speed range is slightly higher than a lower limit of the first speed range. An apparatus is provided to determine the electrical torque of the electrical machine with the aforedescribed method.

主权项

1. A method for determining an electrical torque of an electrical machine having a rotor and a stator in a first high-rotation-speed range and in a second low-rotation-speed range, comprising:
in the first high-rotation-speed range, measuring stator phase currents and stator phase voltages to determine therefrom a stator power and a stator frequency and computing with a defined number of pole pairs of the electrical machine a first electrical torque in the first high-rotation-speed range with a first algorithm; in the second low-rotation-speed range, determining an electrical rotor position angle from the defined number of pole pairs of the electrical machine and a mechanical rotor angle and computing stator flux components from the stator phase currents and the electrical rotor position angle, computing from the stator flux components a second electrical torque in the second low-rotation-speed range with a second algorithm which differs from the first algorithm, wherein an upper limit of the second low-rotation-speed range is slightly higher than a lower limit of the first high-rotation-speed range, defining a safe torque limiting function which limits a maximum permitted torque generated by the electrical machine in the second low-rotation-speed range, and reducing the torque in the second low-rotation-speed range so that the second electrical torque is smaller than the maximum permitted torque.